1994 bobcat 753c

[tkoser]

OK made that crucial mistake of buying something from a family member on their word. Got home only to discover a huge hydraulic leak.

The right drive motor, as I sit on the loader has a leak. The leaks are at the two hex plugs on the face of the motor. I assume they are pressure relief. I took off both caps took out the springs taper caps and check them out. All ok. I replace the O rings on the caps and still leaks. I also notice that the right motor feathers in different then the left. It feathers in nice until about half of the stick movement then it moves quickly.

Things I have done and noticed

All hydraulics have plenty of power. Loader works great
left drive motor is good
Changed filters
no other leaks or issues
4,000 hrs

 

[SSdoxie]

Those 2 plugs on the motor are not relief valves. There is a spool inside the bore from plug to plug. That spool is supposed to shift side to side depending on direction the motor rotates, as it shift it pushes 1 of the tapered cups open allowing case drain oil to re-enter the lower pressure return side of the drive motor loop. This is called the "shuttle valve". If the spool starts to stick, it will be slow to shift over when starting to drive. Symptom will be week drive and soft feel of steering lever when first start moving then a sudden surge of the motor when spool shift fully.
Sometimes polishing the spool will remove scratches and return it to working order, more often it needs to be replaced.
Plus still leak after new O-rings - Inspect the end cap very close looking for cracks at the threads. Be sure you use the right type O-ring, the plug must seal against max. drive pressure of the motor, using too soft of O-ring will not seal it.
Did you also change the metal in-line hydraulic filters (case drain filters) or just the spin on filters. A plugged case drain filter could force the O-ring to leak.
These are Eaton motors, so repair-rebuild parts are fairly easy to find.

 

[tkoser]

ssdoxie

Thanks for the reply. Was beginning to think I was stuck. I did remove the shuttle and the parts. Cleaned and inspected. I saw a very light scratch on the two taper pieces but not bad. I replaced the orings with factory parts. I have not replaced any filters on the tractor. Should I just replace the shuttle and all the parts in it to include the caps and the filters?

 

[tkoser]

was a typo on the first, did not change filters!!